Wind turbines are being developed with large diameter rotors, for example, 200 feet or more, so that each blade may be as much as 100 feet long. Such blades are desirably as light as possible in order to minimize the structure required to support them in operation but also low in cost in order to minimize the installation cost. Since these turbines are located in windy areas and spin on horizontal axes, and the supporting structure must permit the turbine rotor to turn on a vertical axis into the wind, the weight and simplicity of the rotor structure is of greatest importance. Low cost and lightweight blades of adequate stability are thus one of the significant areas for development.